Ipilimumab With or Without Sargramostim in Treating Patients With Stage III or Stage IV Melanoma That Cannot Be Removed by Surgery

This randomized phase II trial is studying how well giving ipilimumab with or without sargramostim (GM-CSF) works in treating patients with stage III or stage IV melanoma that cannot be removed by surgery (unresectable). Ipilimumab works by activating the patient's immune system to fight cancer. Colony-stimulating factors, such as sargramostim, may increase the number of immune cells found in bone marrow or peripheral blood and may help the immune system recover from the side effects of treatment. It is not yet known whether giving ipilimumab together with sargramostim is more effective than ipilimumab alone in treating melanoma.